1. Field of the Invention
The present invention relates to chuck equipments and more particularly to a chuck equipment which can hold insulating substrates.
2. Description of the Related Art
Conventionally, electrostatic chuck equipments have been used to hold substrates in vacuum apparatuses.
A sputtering apparatus, generally denoted at reference numeral 101 in FIG. 9(a), has a vacuum chamber 110. On the top side ceiling of the vacuum chamber 110, there is arranged a target 102. On the bottom wall side, there is arranged a chuck equipment 104.
The chuck equipment 104 comprises a dielectric layer 121 and a pair of electrodes 1221, 1222 embedded in said dielectric layer 121. The chuck equipment 104 also has holes, formed in the dielectric layer 121,and lift pins 106 are inserted into the holes from below.
The electrodes 1221, 1222 are each connected to a chuck equipment power supply 109 which is arranged outside the vacuum chamber 110.
When a substrate 112 is placed on the chuck equipment 104, the substrate 112 opposes in parallel to each of the electrodes 1221, 1222 via the dielectric layer 121, having a thickness of several tens to several hundreds of micrometers disposed between the substrate 112 and the electrodes 1221, 1222.
The substrate 112 such as a silicon or gallium arsenide wafer is electrical conductive. Therefore, when the substrate 112 is placed on the chuck equipment 104, and followed by the power supply 109 turned on, there will be formed a capacitor, designated at reference numeral 1251 in FIG. 9(b), between one of the electrodes 1221 and the substrate 112. There will also be formed another capacitor, designated at reference numeral 1252 in FIG. 9(b), between the other one of the electrodes 1222 and the substrate 112.
These two capacitors 1251, 1252 are connected to the power supply 109 in series with each other. Application of a positive voltage to the one electrode 1221 and a negative voltage to the other electrode 1222 would allow the capacitors 1251, 1252 to be electrically charged. This will cause an electrostatic pressure to be generated between the substrate 112 and the one electrode 1221 and between the substrate 112 and the other electrode 1222. The electrostatic attraction thus generated clamps the substrate 112 electrostatically on the surface of the chuck equipment 104.
With the substrate 112 being clamped electrostatically on the chuck equipment 104, the substrate 112 is in close contact with the chuck equipment 104. This provides higher heat conductivity between the substrate 112 and the chuck equipment 104, thereby making it possible to keep the substrate 112 at a desired temperature using a heating or cooling system equipped with the chuck equipment 104. Therefore, thin film deposition temperatures can be controlled with accuracy upon sputtering the target 102 to form a thin film on the surface of the substrate 112.
Upon completion of the formation of the thin film, the voltage applied to the electrodes 1221, 1222 is disconnected therefrom and the electrostatic clamping of the substrate 112 is released. The lift pins 106 are raised and the substrate 112 is lifted from the chuck equipment 104 and the substrate 112 transferred out of the vacuum chamber 110.
As described above, chuck equipment 104 of the prior-art is adapted to employ the substrate 112 as an electrode to form the capacitors 1251, 1252 between the substrate 112 and the electrodes 1221, 1222 embedded in the chuck equipment 104, thereby generating an electrostatic pressure. Therefore, it is necessary for the substrate 112 to have electrical conductivity so that the substrate can be electrostatically clamped by the chuck equipment 104.
However, it has been lately wanted to perform vacuum processing on glass substrates which constitute liquid crystal display devices or plasma display devices while the glass substrate is being electrostatically clamped on the chuck equipment.
Semiconductor substrates formed of a single crystal have electrical conductivity even with a high resistance, thus making it possible to generate an electrostatic pressure for clamping the substrate on the chuck equipment. However, glass substrates have too high insulation to form the capacitors shown in FIG. 9(b), thereby allowing the substrate not to be electrostatically clamped on the chuck equipment 104.
The present invention was developed to solve the aforementioned prior-art problems and an object thereof is to provide a chuck equipment which can hold insulating substrates.
The present invention is a chuck equipment comprising a plate-shaped base, a first electrode to which a first voltage is applied, and a second electrode to which a second voltage different from said first voltage in magnitude is applied, the first and second electrodes being insulated from each other and arranged on a surface of the base.
The present invention is the chuck equipment, in which surfaces of the first and second electrodes can be exposed.
The chuck equipment of the present invention is constructed in such a manner that a substrate may be placed on the surface of the chuck equipment on which the first and second electrodes are arranged to cause the substrate to be brought into contact with the first and second electrodes.
The chuck equipment of the present invention is characterized in that the surface of the base is even with the surfaces of the first and second electrodes.
According to the chuck equipment of the present invention, an insulating convexity portion can be arranged between the first and second electrodes.
According to the chuck equipment of the present invention, the first and second electrodes can have a protective film arranged on the surfaces thereof.
The chuck equipment of the present invention may be constructed in such a manner that a substrate may be placed on the surface of the chuck equipment on which the first and second electrodes are arranged to cause the substrate to be brought into contact with the protective film formed on the first and second electrodes.
According to the chuck equipment of the present invention, the first electrode can be spaced apart from the second electrode by 2 mm or less.
According to the chuck equipment of the present invention, the first and second electrodes can be made 4 mm or less in width.
The chuck equipment according to the present invention may comprise a plurality of the first and second electrodes arranged thereon, and regions where the first and second electrodes are alternately arranged.
The chuck equipment according to the present invention may have a third electrode to which a third voltage different from first and second voltages is applied.
Furthermore, the present invention also provides a vacuum processing apparatus comprising a vacuum chamber in which the above-described chuck equipment of the present invention is arranged.
The vacuum processing apparatus according to the present invention may comprise a power supply for establishing an electric field of 1.0xc3x97106 V/m or greater between the first and second electrodes.
According to the vacuum processing apparatus of the present invention, a protective plate may be arranged around the chuck equipment, and a substrate may be placed on the chuck equipment to cause the substrate to be accommodated in the protective plate.